The increase in integration density of semiconductor devices has led to the decrease of design rules. Thus, a photomask pattern to be transferred to a wafer may be formed in various shapes in order to meet these decreased design rules. Photomask patterns may be generated using exposure systems. Examples of exposure systems are disclosed by commonly assigned U.S. Pat. Nos. 7,629,087 to Huh et al., 7,518,704 to Kim et al., 7,463,333 to Park et al., 6,960,414 to Park et al. and 5,978,138 to Kang et al., the disclosures of which are hereby incorporated herein by reference.